The present invention relates generally to agricultural combines. It relates particularly to a trailer towing system for agricultural combines.
An agricultural combine is a common and well-known machine for harvesting crop materials. Agricultural combines are available in various designs and models to perform the basic functions of reaping crop materials from a crop field, separating the grain from the non-grain crop materials, and discarding the non-grain crop materials back onto the crop field.
A typical combine includes a crop harvesting apparatus, or header, which reaps ripened crop plants from the crop field and feeds the crop materials to a separating or threshing system. Several different types of threshing systems are available, such as rotary threshers and straw walkers. Regardless of the type of threshing system used, the thresher separates the course non-grain materials from the grain heads. The course non-grain material primarily consists of grain stalks and exits the threshing system along its rear end. The grain heads, on the other hand, exit the thresher along the bottom of the threshing assembly and pass to a series of moving sieves. The sieves separate the grain from the unwanted fine materials, sometimes referred to as chaff. After separation, the: grain is directed to a grain bin through an augering system, and the unwanted fine materials exit the sieves along the rear end.
The agricultural economy continues to pressure farmers to be more efficient in their farming practices. One area that is of particular concern to farmers is the harvesting operations because of the dramatic impact that the harvest can have on a farm""s success. Typically, farmers prefer that harvesting operations proceed as quickly as possible. One reason that a quick harvest is desirable is the unpredictability of the weather and the risk of losing a portion of the crop due to rains, snow, wind, or hail. Another reason for this urgency is the high cost of the harvesting operation, which includes the cost of combines, trucks, and labor. By operating quickly and efficiently, a farmer can lower the cost of the harvesting operation by harvesting a larger area of land with the same equipment and manpower.
A development in harvesting practices that has increased overall efficiency is the use of grain carts. Grain carts are trailers that have large grain bins for storing the harvested grain. In the past, combines were commonly forced to cease harvesting when the onboard storage bin of a combine became filled with grain but a truck was unavailable for unloading the grain. Unavailability of a truck at the proper time is a common problem when travel distances are long, an insufficient number of trucks are supplied or the crew is short of drivers. This situation frequently results in the combine sitting idle while it waits for a truck to arrive. The idle time that results is costly because less acreage is harvested during a given period of time.
Grain carts have improved this problem by providing an interim storage location in which the combine can unload its own onboard grain bin when it becomes full. The grain cart can then independently fill the trucks when they are available. Typically, grain carts are unpropelled trailers that are towed by agricultural tractors. Agricultural tractors are most often chosen by farmers for pulling the grain carts because they are already designed for pulling heavy loads. Such tractors are usually available during harvest season because they are not needed for other farm operations.
The use of an agricultural tractor to tow the grain cart is not always the most efficient option however. A grain cart typically does not fully utilize the tractor""s load pulling capacity because of the relatively light load of the grain cart. This can have a negative impact on the resale value of the tractor because the age of agricultural tractors is based solely on hours of usage. In addition, while many farmers may have an extra tractor available during harvest season, some farmers may not have tractors freely available.
The tractor problem also affects contract combine operators who harvest on a custom basis and travel from state to state during the nation""s harvest season. These operators must purchase an additional tractor to tow the grain cart and must transport this extra piece of equipment from site to site. Another problem with using an agricultural tractor to tow a grain cart occurs when a contract operator runs a large fleet of combines. In this situation, it is desirable to use several grain carts. However, this requires additional tractors, which would raise costs even further.
A more efficient solution for towing a grain cart is to use the combine itself. This solution has several advantages. An extra towing vehicle, like the agricultural tractor, is unneeded. Manpower required is decreased because an additional driver for the towing vehicle is no longer needed. Furthermore, .additional grain carts can be used to further increase efficiency. For example, when a separate towing vehicle is used, the number of grain carts used in an operation is usually reduced because of the extra cost of the towing vehicles. Thus, a single grain cart usually services several combines. However, when the grain cart is towed directly by the combine, each combine can be served by its own grain cart because the grain carts themselves are relatively inexpensive.
Using the combine as the towing vehicle has historically had some disadvantages however. In known combines, the drawbar of the grain cart is attached to the combine at a connection point near the rear axle. This connection point has traditionally been provided by manufacturers for towing a trailer that carries the combine""s header in a lengthwise orientation from site to site. However, because this connection point is positioned below the crop residue discharge opening, additional problems are created when a grain cart is towed. Because the drawbar of the grain cart obstructs the path of the crop residue as it travels between the combine""s discharge opening and the ground, the combine is unable to evenly spread the crop residue onto the crop field. Modern farming practices require an even spread of the crop residue across the entire field. This is especially true with the recent practice of no-till farming, but also remains important for more traditional farming techniques. However, when the path of the crop residue is obstructed by the grain cart""s drawbar, the resulting blanket of residue on the field is uneven, with some areas having thicker sections of residue and other areas having thinner sections.
Another problem is that some of the crop residue builds up on the grain cart""s drawbar. This buildup tends to compact itself on the drawbar into mounds of residue until they eventually break loose from the drawbar and fall to the ground. As a result, the farmer""s field is left with a number of these compact mounds of residue scattered throughout the field. This result is unattractive and causes further difficulties for the farmer when trying to evenly till the ground.
Still another problem arises because weed seeds are carried from field to field. This problem has become one of increasing concern to farmers as noxious weeds continue to spread over larger regions of farm land. The difficulty and expense of controlling noxious weeds once they become established makes it important to prevent the introduction of these weeds into uninfected fields. Farmers have increasingly begun to recognize that the spread of these noxious weeds can be minimized by cleaning their agricultural equipment of stray crop residue before transporting from field to field. This practice prevents weed seeds from one field from being inadvertently transplanted into an uninfected field from an infected field. However, the cleaning process is laborious and often overlooked. Farmers would therefore prefer to minimize the number of places where crop residue can accumulate and be transported from one field to another.
This problem of crop residue buildup on the grain cart drawbar also has the potential for fostering equipment fires. Fires during the harvest season are not infrequent occurrences. Typically, the weather is especially dry during the harvest season with the crops being equally dry. With this combination of dry conditions and a flurry of harvesting activity occurring, it is not uncommon for farmers to loose equipment in a fire. Any excess buildup of crop residue on the equipment, therefore, is undesirable because this buildup could potentially serve as an original source of a fire or may sustain a fire that has already started.
Finally, the general appearance of the farmer""s equipment is adversely affected when the combine discharges crop residue onto the grain cart drawbar. Farmers tend to take a great deal of pride in their equipment and prefer to keep it in good condition and looking new. However, when crop residue sprays onto the drawbar, the residue can become encrusted onto the surface of the drawbar so that it becomes difficult to fully clean off. In some cases, where the combine sprays the residue out at a high speed and the manufacturer of the grain cart uses a low quality paint, the paint on the drawbar can even be stripped away. Thus, farmers prefer equipment that is relatively self-cleaning.
Accordingly, it is an object of the invention to provide an improved system for connecting a grain cart and a combine.
It is a further object of the invention to provide a combine and grain cart with a connecting system including an elevated drawbar so that the crop residue will be discharged below the drawbar.
According to the invention, a connecting system includes a drawbar which is connected to the combine above the combine""s crop residue discharge opening. Several different connection mechanisms may be provided for attaching the grain cart drawbar to the rear end of the combine. These mechanisms may include a pin and clevis, ball joint, pintle hitch, or a rigid connection. A vertical section of the drawbar may also be used in combination with a shield to further direct the crop residue in a desired direction. The shield can be formed in different shapes so that the crop residue is directed in a variety of directions, including downwards or to the sides.